The present invention relates generally to electric motor powered vacuum cleaners and specifically to the motor control of an electric vacuum cleaner which has a separate electric motor powered rotary brush.
Vacuum cleaners are known which have a roller-shaped brush which is rotatingly mounted in the nozzle opening of the vacuum cleaner. The brush may be driven by a motor mounted in the housing of the brush device by means of a belt drive. Electrical energy required for running the electric motor is obtained by means of a connecting line to the circuit of the vacuum-generating motor with both motors being operated together. Both motors, connected in parallel, are generally connected to an electrical power supply (house current) by a power line.
In these prior art brush-equipped vacuum cleaners, the drive motor and thus the brush itself is operated only at a single rotational rate.
The use of the roller-shaped brush device in combination with the vacuum cleaner on textile floor coverings of different types makes it necessary to adjust the rpm of the roller-shaped brush to the particular type of floor covering in order to achieve optimum cleaning performance. These different floor coverings also lead to widely differing loads on the brush with the long-pile "shag" carpet presenting a substantially greater load to the brush motor than does a shorter-pile or "cut-pile" floor covering.